What it does
The Check Engine Light function turns on a dash warning lamp when the Nexus logs Diagnostic Trouble Codes (DTCs), faults like a sensor out of range or an open injector circuit. It gives the driver a clear sign to plug in a laptop or call us, instead of finding the fault in a log weeks later.
Activation criteria
| Option | Light turns on when | Best for |
|---|---|---|
| Current DTCs only | A fault is present during this key cycle. A new drive starts with the light off | Race cars and development, where you only care about what's wrong now |
| Current and past DTCs | A fault is present now, and the light stays on while any DTC remains stored, even after the fault goes away | Street cars, so an intermittent fault isn't forgotten |
For most customer cars we prefer current and past. An intermittent fault may only show up on a hot day or over bumps, and a light that stays on until the code is read and cleared means it gets looked at.
Next steps
Wiring the lamp is covered in check engine light wiring. When the light comes on, look the code up in the DTC index. Other vehicle-side functions are listed under Vehicle Functions. On an Elite, see check engine light for Elite.
